From 7957c5a92b19dde4ad440cc0720c60373fb3b46c Mon Sep 17 00:00:00 2001
From: Elizabeth Engelman <emengelman@gmail.com>
Date: Wed, 28 Nov 2018 16:15:19 -0600
Subject: [PATCH] Add a state diff service

---
 cmd/geth/usage.go    |  6 +++++
 cmd/utils/flags.go   | 13 +++++++++++
 statediff/service.go | 54 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 73 insertions(+)
 create mode 100644 statediff/service.go

diff --git a/cmd/geth/usage.go b/cmd/geth/usage.go
index 82f17e0ee..152ac059b 100644
--- a/cmd/geth/usage.go
+++ b/cmd/geth/usage.go
@@ -245,6 +245,12 @@ var AppHelpFlagGroups = []flagGroup{
 			utils.MinerLegacyExtraDataFlag,
 		},
 	},
+	{
+		Name: "STATE DIFF",
+		Flags: []cli.Flag{
+			utils.StateDiffFlag,
+		},
+	},
 	{
 		Name: "MISC",
 	},
diff --git a/cmd/utils/flags.go b/cmd/utils/flags.go
index c18d98383..b16f9cdca 100644
--- a/cmd/utils/flags.go
+++ b/cmd/utils/flags.go
@@ -58,6 +58,7 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 	whisper "github.com/ethereum/go-ethereum/whisper/whisperv6"
 	"gopkg.in/urfave/cli.v1"
+	"github.com/ethereum/go-ethereum/statediff"
 )
 
 var (
@@ -1338,6 +1339,18 @@ func RegisterEthStatsService(stack *node.Node, url string) {
 	}
 }
 
+func RegisterStateDiffService(stack *node.Node) {
+	if err := stack.Register(func(ctx *node.ServiceContext) (node.Service, error) {
+		var ethServ *eth.Ethereum
+		ctx.Service(&ethServ)
+		chainDb := ethServ.ChainDb()
+		blockChain := ethServ.BlockChain()
+		return statediff.NewStateDiffService(chainDb, blockChain)
+	}); err != nil {
+		Fatalf("Failed to register State Diff Service", err)
+	}
+}
+
 func SetupMetrics(ctx *cli.Context) {
 	if metrics.Enabled {
 		log.Info("Enabling metrics collection")
diff --git a/statediff/service.go b/statediff/service.go
new file mode 100644
index 000000000..695e3d638
--- /dev/null
+++ b/statediff/service.go
@@ -0,0 +1,54 @@
+package statediff
+
+import (
+	"github.com/ethereum/go-ethereum/p2p"
+	"github.com/ethereum/go-ethereum/rpc"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"fmt"
+)
+
+type StateDiffService struct {
+	builder    *builder
+	extractor  *extractor
+	blockchain *core.BlockChain
+}
+
+func NewStateDiffService(db ethdb.Database, blockChain *core.BlockChain) (*StateDiffService, error) {
+	config := Config{}
+	extractor, _ := NewExtractor(db, config)
+	return &StateDiffService{
+		blockchain: blockChain,
+		extractor: extractor,
+	}, nil
+}
+
+func (StateDiffService) Protocols() []p2p.Protocol {
+	return []p2p.Protocol{}
+
+}
+
+func (StateDiffService) APIs() []rpc.API {
+	return []rpc.API{}
+}
+
+func (sds *StateDiffService) Start(server *p2p.Server) error {
+	fmt.Println("starting the state diff service")
+	blockChannel := make(chan core.ChainHeadEvent)
+	sds.blockchain.SubscribeChainHeadEvent(blockChannel)
+	for {
+		select {
+		case <-blockChannel:
+			headOfChainEvent := <-blockChannel
+			previousBlock := headOfChainEvent.Block
+			//TODO: figure out the best way to get the previous block
+			currentBlock := headOfChainEvent.Block
+			sds.extractor.ExtractStateDiff(*previousBlock, *currentBlock)
+		}
+	}
+	return nil
+}
+func (StateDiffService) Stop() error {
+	fmt.Println("stopping the state diff service")
+	return nil
+}
\ No newline at end of file